数学三角函数诱导公式题
\u4e09\u89d2\u51fd\u6570\u8bf1\u5bfc\u516c\u5f0f\u9898(1)\u539f\u5f0f\uff1dcos(\u03c0/5)\uff0b cos(2\u03c0/5)- cos(2\u03c0/5)-cos(\u03c0/5)\uff1d0 cos(\u03c0-\u03b1)\uff1d-cos\u03b1
(2)\u539f\u5f0f\uff1d0 tan(\u03c0-\u03b1)\uff1d-tan\u03b1 sin(\u03c0-\u03b1)\uff1dsin\u03b1
\u5373-2tana+3sinb+5=0
tana-6sinb-1=0
\u6240\u4ee5sinb=1/3,tana=3
sina/cosa=tana=3
cosa=1/3*sina
cos²a=1/9*sin²a
\u56e0\u4e3asi²a+cos²a=1
\u6240\u4ee5sin²a=9/10
a\u662f\u9510\u89d2\u5219sina>0
sina=3\u221a10/10
cos（π/6-x）=-1/3
cosπ/6*cosx+sinπ/6*sinx=-1/3
根号3/2cosx+1/2sinx=-1/3
cos（5π/6+x）=cos5π/6*cosx-sin5π/6*sinx
=-（根号3/2cosx+1/2sinx）
=1/3
绛旓細璁疚变负浠绘剰瑙,缁堣竟鐩稿悓鐨勮鐨勫悓涓涓夎鍑芥暟鐨勫肩浉绛: sin(2k蟺+伪)=sin伪 cos(2k蟺+伪)=cos伪 tan(2k蟺+伪)=tan伪 cot(2k蟺+伪)=cot伪 鍏紡浜: 璁疚变负浠绘剰瑙,蟺+伪鐨勪笁瑙掑嚱鏁板间笌伪鐨勪笁瑙掑嚱鏁板间箣闂寸殑鍏崇郴: sin(蟺+伪)=-sin伪 cos(蟺+伪)=-cos伪 tan(蟺+伪)=tan伪 cot(蟺...
绛旓細鍋囧鏈変竴涓洿瑙涓夎褰 ABC,鍏朵腑 a銆乥 鏄洿瑙掕竟锛宑 鏄枩杈广傛寮(sin)绛変簬瀵硅竟姣旀枩杈;sinA=a/c锛涗綑寮(cos)绛変簬閭昏竟姣旀枩杈;cosA=b/c锛涙鍒(tan)绛変簬瀵硅竟姣旈偦杈;tanA=a/b銆
绛旓細cos锛埾+a锛=-cosa=-1/2,cosa=1/2 a鍦ㄧ鍥涜薄闄 鎵浠ina<0 sin²a+cos²a=1 sina=-鈭3/2 sin(2蟺-a)=sin(-a)=-sina=鈭3/2 2銆乻in(2蟺-a)=sin(-a)=-sina 5cos锛2蟺-a锛/2cos(蟺+a)=5cos(-a)/2(-cosa)=5cosa/(-2cosa)=-5/2 sin(-a)=-sina 鎵...
绛旓細.璇卞鍏紡 sin(-a)=-sin(a) cos(-a)=cos(a) sin(蟺2-a)=cos(a) cos(蟺2-a)=sin(a) sin(蟺2+a)=cos(a) cos(蟺2+a)=-sin(a) sin(蟺-a)=sin(a) cos(蟺-a)=-cos(a) sin(蟺+a)=-sin(a) cos(蟺+a)=-cos(a) tgA=tanA=sinAcosA 2.涓よ鍜屼笌宸殑涓夎鍑芥暟 sin(...
绛旓細鍥炵瓟锛氶澶寸湅涓嶆竻銆
绛旓細sin锛埾/2-a锛=cosa銆傚熀鏈璇卞鍏紡銆傚垎鏋愯繃绋嬪涓嬶細鐢讳竴涓洿瑙涓夎褰紝纭畾涓涓攼瑙掓槸a锛屽垯锛宑osa鏄痑鐨勪复杈规瘮鏂滆竟锛岄偅涔堝彟涓涓攼瑙掑氨鏄/2-a锛屽浜庨偅涓鏉ヨ锛屽氨鏄杈规瘮鏂滆竟锛屽氨鏄寮︿簡銆
绛旓細sin300搴=sin(360搴-60搴)=-sin60搴=-鈭3/2 cos10蟺/3=cos(4蟺-2蟺/3)=-cos蟺/3=-1/2 sim11蟺/4=sin(2蟺+3蟺/4)=sin3蟺//4=sim(蟺-蟺/4)=sin蟺/4=鈭2/2 tan锛堬紞1560搴︼級=tan(-4X360搴-120搴)=tan(-120搴)=-tan(180搴-60搴)=tan60搴=鈭3 ...
绛旓細cos(蟺+伪)锛-cos伪 tan(蟺+伪)锛漷an伪 3.涓夎鍑芥暟璇卞鍏紡涓夛細sin(蟺-伪)锛漵in伪 cos(蟺-伪)锛-cos伪 tan(蟺-伪)锛-tan伪 4.涓夎鍑芥暟璇卞鍏紡鍥涳細缁堣竟鐩稿悓鐨勮鐨勫悓涓涓夎鍑芥暟鐨勫肩浉绛.2k蟺+ 瑙勫緥锛2k蟺鍏ㄦ锛岃礋瑙掍綑寮︽锛屜鍔犳鍒囨锛屜鍑忔寮︽.瀵圭収鐫璇卞鍏紡鍐嶇湅鐪棰樼洰锛岃兘鏄庣櫧鍚...
绛旓細1.sin(-120 掳锛=-sin(120 掳)=-sin(180 掳-60 掳)=-sin60 掳=-鈭3/2 2.cos(-4蟺/3 )=cos(4蟺/3)=cos(蟺+蟺/3)=-cos(蟺/3)=-1/2 3.tan17蟺/6 =tan(3蟺-蟺/6)=tan(-蟺/6)=-tan(蟺/6)=-鈭3/3 4.cos (-135掳)=cos锛135 掳)=cos(180掳-45掳)=-cos45...
绛旓細1.cos(a-蟺/2)/sin(5蟺/2 +a) 脳 sin(a-2蟺) 脳 cos(2蟺-a)瑙ｏ細鍘熷紡=sina/sin(蟺/2+a )脳 sin(a) 脳 cos(-a)=sina/cos(a )脳 sin(a) 脳 cos(a)=sin^2(a)2.cos²锛-a锛- tan(360掳+a)/sin(-a)瑙ｏ細鍘熷紡=cos²锛坅...
